hedtmann etal



Feb. 9, 1960 E. HEDTMANN ET AL MAGNETIC BOBBIN BRAKE FOR DOUBLE TWIST SPINDLES FIG. I

Filed July 12, 1954 INVENTOR EUGEN HEDTMANN WALTER BUHROW 'v u U, LC 4% ATTORNEY United States MAGNETIC BOBBIN BRAKE FOR DOUBLE TWIST SPINDLES Application July 12, 1954, Serial No. 442,876 Claims priority, application Germany July 14, 1953 4 Claims. (Cl. 57-58.76)

This invention relates to double twist spindles, and more particularly to magnetic brakes for arresting undesired rotary displacement of the bobbins used in double twist spindles.

In the spinning art it has been customary to stop or look the bobbins of vertical double-twist spindles by means of permanent magnets or electromagnets. To this end one has arranged on the spindle housing, outside the outer balloon of the yarn a permanent magnet or an electromagnet, for magnetic interaction with corresponding counter-magnets or soft iron armatures which are arranged in fixed position on the normally stationary carrier for the bobbin.

These bobbin carriers at times are exposed to sudden shock-like vibrations due, for example, to tangled filaments on the bobbin. These vibrations cause the bobbin carrier to be displaced from its position of rest so that, if the magnetic field action between the corresponding magnets is not sufficiently strong, the bobbin carrier will not find its way back to its position of rest, but will start revolving, or oscillating about its position of rest, in which event additional impulses of the same kind, or other impulses deriving from the device or the drive therefor, are bound to build up the oscillation to a point where revolution results also.

In consequence of this rotary displacement of the bobbin carrier, the device has to be stopped temporarily. However, even after the device has been stopped, if the prevailing position of the magnet could not be discerned and no markings could be provided on the exterior surface of the bobbin carrier, it was not possible, without many difiiculties and loss of time, to turn the magnet and counter-magnet or soft iron armature back into their corresponding positions.

Because of these difiiculties, the art proceeded to pro vide double-twist spindles with magnets of greater force with alternating opposite poles. This arrangement provided for a stronger magnetic locking action in the position of rest and it tended to facilitate the return of the bobbin carrier, once it had been displaced, into its position of rest by magnetic repellent action. These expedients proved satisfactory as long as the spindle was at rest, but as soon as it started operating and the bobbin carrier was displaced from its normal position, one never could be certain that owing to the influence of bearing friction or after the generation of vibration the bobbin would find its way back to its normal position.

Further, in order to insure the safe operation of the double-twist spindles provided with magnetic fixatio'n means, locking devices had to be provided for operation, for example, as soon as the mutually tuned magnets were no longer in proper juxtaposition. These locking devices as a rule acted directly on the bobbin carrier by means of brakes resulting in tear of the yarn in the outer balloon; other devices simply shut ofi the drive for the double twist spindle.

While the above-noted prior art devices prevented rent 2,924,064 Patented Feb. 9, 1960 double-twist cabling spindles with magnetic stopping means from being damaged, nevertheless even a small deviation of the bobbin, from its normal position, which could not be corrected by the magnetic devices proposed so far, always required a temporary stop of the double twist spindle, thus resulting in a most undesirable interruption of operations.

It is an object of this invention to provide a magnetic bobbin brake for double twist spindles which eliminates the drawbacks enumerated above.

Other objects, and the manner in which the same are attained, will become apparent as this specification proceeds.

The present invention contemplates supporting the permanent magnet or soft iron armature disposed on the bobbin carrier, so it is displaceable with respect to said carrier. According to the invention, if a shock causes a displacement of the bobbin carrier, the magnet mounted on it is carried along through a small angle until the tangential force component resulting from the magnetic field action exceeds the frictional resistance of the magnet on the bobbin carrier. As soon as this condition is met, the magnet will move no further whereas the carrier will continue its movement until under the influence of the frictional force deriving from the arrested magnet, it, too, will come to a standstill.

With this displaceable arrangement of the magnet or armature on thebobbin carrier, the magnet or armature can no longer be removed from the field of action of the stationary outer magnet by shocks of any magnitude. This applies also in thecase where the bobbin carrier is set to oscillate about the zero position of the magnet. Up to a maximum amplitude which, as noted above, depends on the magnetic field efiect and the frictional resistance between the magnet and the carrier, the magnet and the carrier will oscillate or rotate, but as the amplitude becomes greater, the friction between the arrested magnet and the carrier will exert a braking and damping influence on the vibrations. Consequently, a build-up of oscillations will be possible only up to a certain limit, whereafter all oscillatory energies will be damped.

Consequently, the movable support of the magnet according to this invention is effective in preventing the bobbin carrier from engaging in any sustained rotation following a shock-prompted displacement of an oscillatory or rotary character. The bobbin is no longer locked in any one position as in prior art devices, but is free to yield to any shocks, with any excess energy absorbed not by a permanent rotation but by a conversion into frictional heat. Only in response to very material deviation forces which exceed the braking moment of the magnet support, caused, for example, by excessive friction between the bobbin carrier and the rapidly revolving spindle, even the present bobbins may start revolving slowly. In this rare event, it will still be necessary to arrest the spindle and repair it.

Of particular importance for the proper functioning of this movable arrangement of the magnets is the friction factor of the surfaces engaging one another, of the magnet or soft iron armature and the bobbin carrier, respec tively. This factor should be so selected that the magnet on the bobbin carrier will remain under the influence of the outer magnet. This factor can be varied by a corresponding variation of the materials of which the parts are made, or by a variation of the qualities of the braking surfaces or also by means of lubricants. Any increase of the magnetic field action will also increase the braking action on the bobbin carrier.

Thus the advantages offered by a device according to this invention are characterized, as far as the position of rest is concerned, by a constant readiness of the spindle since the magnets always correspond, and under working conditions, where displacements from the rest position occur, by the bobbin yielding to every angular momenturn, but immediate braking of the rotary movement, when a predetermined limit for the displacement of the magnet has been reached, up to complete stoppage of the bobbin and further by impeding any oscillations of the bobbin beyond a predetermined amplitude by damping. Thus a double twist spindle provided with the magnetic bobbin brake according to this invention will be far less subject to any disturbances than the double twist spindles of the prior art.

In the drawings afiixed to this specification and forming part thereof, several embodiments of a double twist spindle incorporating the present magnetic bobbin brakes are illustrated quite schematically by way of example.

In the drawings,

Fig. 1 is a purely diagrammatic section along line I-I in Fig. 2, illustrating only such essential parts as are necessary to indicate the relative displacement of the several parts;

Fig. 2 is a sectional side view of a double twist spindle according to the invention, and

Fig. 3 is a similar sectional side view of a modification.

Referring to the drawings, and first to Fig. l, the normally stationary carrier for the supply bobbin is indicated at 1. A first, stationary magnet which may be fixedly mounted on the spindle support, is shown at 2, While 3 denotes the second magnet arranged for frictional displacement with respect to the supply bobbin carrier 1. Owing to the effect of the magnetic forces, the second magnet 3 is normally at rest in a position just opposite the stationary first magnet 2 with its arched face pressed against the circumference of the carrier 1. If, under the influence of a sudden rotary displacement, the supply bobbin carrier is caused to move in the direction of the arrow, the second magnet 3 is first taken along, but when the tangential force component resulting from the magnetic field action overcomes the friction between it and the carrier, it will be arrested in the position indicated in dotted lines at 4, with the result that the increased friction now prevailing between the second magnet 3 and the circumferential rim portion of the supply bobbin carrier 1 will brake and ultimately arrest the rotary displacement of the carrier. Unless the force responsible for the rotary displacement of the carrier has a continuously active character, and unless this force exceeds a certain value, the supply bobbin carrier is bound to be braked and arrested by the friction with the arrested second magnet 3, without it being necessary to stop the spindle and thus interrupt operations altogether.

As shown in Fig. 2, the first, stationary magnet 2 may be mounted, by means of a bracket 6, on the support 20 for the spindle. The second magnet or iron armature 3 is supported for displacement on the bobbin carrier generally indicated at 1 which comprises a body portion 11 and a groove wherein the magnet 3 is disposed for sliding displacement. The rotary portion of the double twist spindle is shown at 5. In addition to the parts already mentioned, the double twist spindle comprises the driving whorl 12, the thread storage disk 13, the in-let portion 14, the bobbin 15, the bearing 17 interposed between the spindle and the bobbin, the spindle shaft 18 and the exit channel 19 in the thread storage disk 13. The twisting spindle itself is supported, by means of ball hearings, in the support 20. The yarn is shown at 16, and its path through the device is clearly shown in Fig. 2. The portion 5 rotates along with the thread storage disk 13 and the spindle shaft 18, while the bobbin carrier 1, with its portions 10 and 11, is normally stationary, except when it is set to oscillate or rotate under the influence of outside forces, in which case it is braked and its movement arrested by the magnetic bobbin brake according to the invention.

According to the modification shown in Fig. 3, the stationary magnet 22 is mounted on a bracket 26 which in turn, may be mounted on a support corresponding to the support shown at 20 in Fig. 2, while the movable magnet 23 is mounted for displacement on the normally stationary bobbin carrier 31, by means of a lever arm 27 mounted on a brake ring 29 which is movably supported in an annular groove of a brake disk 28 forming part of the bobbin carrier 31.

We wish it to be understood that we do not desire to be limited to the details described in the foregoing specification and shown in the drawings for obvious modifications will occur to a person skilled in the art.

We claim:

1. A double twist spindle comprising in combination, a twisting spindle, a support for said twisting spindle, a first magnet firmly mounted on said support, a normally stationary carrier for the bobbin freely mounted on said twisting spindle so as to permit the relative rotary motion of said spindle, and a second magnet mounted on said bobbin carrier for displacement with respect to said carrier, whereby on an abnormal rotary displacement of the bobbin carrier, said second magnet is taken along by said carrier until the tangential force component resulting from the magnetic field action overcomes the friction between said second magnet and said carrier, so as to arrest said second magnet and thereby, in turn, brake and arrest the rotary displacement of said carrier.

2. A double twist cabling spindle according to claim 1, wherein the second magnet is replaced by a soft iron armature.

3. A double twist spindle according to claim 1, wherein the bobbin carrier includes a circumferential groove, and the second magnet is arranged for sliding displacement in said groo've.

4. A double twist spindle according to claim 1, wherein the bobbin carrier includes a brake portion comprising a groove and a brake ring arranged in said groove, and the second magnet is linked to said brake ring.

References Cited in the file of this patent UNITED STATES PATENTS 1,949,621 Pool Mar. 6, 1934 2,463,636 Meade Mar. 8, 1949 2,507,573 Oetzel May 16, 1950 2,534,496 Agresti Dec. 19, 1950 2,605,602 Koella Aug. 5, 1952 2,641,896 Landolt June 16, 1953 2,692,471 7 Landolt u Oct. 26, 1954 FOREIGN PATENTS 872,986 France Mar. 2, 1942 

